Wikipedia:Reference desk/Archives/Science/2023 August 16

= August 16 =

Baidana = bullshit?
Question about chain mail: I've known for a while about a type of chain mail called "baidana", which was allegedly used by some Russian knights in the late Middle Ages, and which was made of large-diameter rings (much larger than normal, and so large that you can literally see through it). So, the question is, what's the point of such an armor? Because, due to the rings being so wide, it would offer no protection whatsoever against arrows and very little protection against stabbing attacks, and would also have less flexibility than normal chain mail (which would offset its admittedly lighter weight, which, along with its lower cost, are the only advantages I can see of this type of armor) -- am I correct? 2601:646:9882:46E0:4579:586D:A5CF:72A3 (talk) 06:37, 16 August 2023 (UTC)


 * The baidana said to be of Boris Gudonov seen here does not appear to have dramatically larger open spaces than typical chain mail. What is also important is the inner diameter of the rings, which should ideally be almost half the outer diameter. If $D$ is the outer diameter and $d$ is the inner diameter, the size of the open spaces is characterized by the value of $2d − D$. I do not know to what extent longbows and pikes were used in medieval Russian warfare; a small size does not seem that important for protection in a sword fight. Perhaps some less effective forms of chain were meant to be used as part of a ceremonial dress. --Lambiam 08:17, 16 August 2023 (UTC)
 * Looking at the image on that page, and the dimensions given, I don't think it would be very easy to get an arrow through the gaps. You have an 11 to 15mm inner diameter (depending on the armour), and much of that gap will be filled in with parts of the other rings.  The rings are also thicker than I think is typical for chain mail, at least in the case of the with with 2.5mm thickness.  So I expect they are improving strength (and probably ease of manufacture) at the expense of flexibility and protection against extremely narrow points.  Also, they have prayers inscribed on the rings, granting a +1 Holy bonus to AC . Iapetus (talk) 11:51, 16 August 2023 (UTC)

WW2 attack fighters
Did any attack-fighters used in World War 2 have any kind of spaced armor, cemented and/or face-hardened armor? In particular, was any armor of this type (or indeed, any other than rolled homogeneous armor) ever fitted to any version of the Russian Il-2 or Il-10, even as a one-off experiment? 2601:646:9882:46E0:4579:586D:A5CF:72A3 (talk) 06:42, 16 August 2023 (UTC)
 * I can't speak as to one-offs, but I suspect the Ilyushin's design somewhat answers your question in the negative: it had a reputation as one of (or indeed, probably the) most resilient ground-attack aircraft of the war, with nicknames like the "concrete plane", "the flying tank", and "The Beast" in various iterations, and yet, according to this source, it seems to have only utilized conventional plating--just lots of it:
 * "The Il-2 was anything but advanced in its mixed wood-and-metal construction, which was relatively easy to manufacture in significant numbers using relatively unskilled workers. But for an aircraft, it was an amazing achievement. Among the Shturmovik’s most important assets were its strength and robustness in combat. The forward fuselage section — protecting the aircraft’s fuel system, radiators and crew station — was built entirely of armor plate. Thus, the Il-2 could, and often did, absorb extraordinary battle damage and survive to fight another day. The protective armor shell employed a special alloy developed for the Il-2; its thickness varied by location on the airframe. Special consideration had been given to a technology that would allow maintenance personnel to stamp the armor steel in the field, thus providing flexibility in the design, especially when Soviet units were forced to operate from primitive forward battle areas."
 * SnowRise let's rap 07:46, 16 August 2023 (UTC)
 * On the subject of armor for warplanes, it would be interesting to learn whether the WW2 Russian air force ever learned the following strategy. Conventional wisdom was to observe what areas of fighter planes that survive airborne dogfights get damaged most and to add armor to those areas. A later realization in the West was that strengthening other parts of planes reduced casualties more effectively because planes hit on those areas were never seen to survive. Philvoids (talk) 16:30, 16 August 2023 (UTC)
 * The source cited above does speak a little bit to this, and there does seem to have been some modular adaptation to such needs, but the Ilyushin was so often deployed for very low altitude strafing runs against reinforced positions, that it doesn't seem there were many places on the frame where it wouldn't take some degree of anti-aircraft fire. Similarly, there are some threats that no (realistic) amount of armour was ever going to significantly mitigate: for example, the greatest threat the the Shturmovik's safe return from a sortie seems to have been aircraft fire to the tail, owing to one weakness in soviet airpower relative to the luftwaffe:  escort fighters. Sn<b style="color:#99d5fe;">o</b><b style="color:#b2dffe;">w</b><b style="color:#B27EB2;">Rise</b><b style="color:#d4143a"> let's rap</b> 19:39, 16 August 2023 (UTC)


 * As I understand it, spaced armour was introduced to defeat high-explosive anti-tank ammunition which works on the shaped charge principle. Not much used against aircraft I imagine. Alansplodge (talk) 22:11, 17 August 2023 (UTC)


 * Not really in the same way, no--although there is a similar application of a proximity fuze for flak weapons. By the late Pacific campaign in particular, American vessels were using such weapons very regularly.  But there the idea was just to get the ordinance to explode over a typically greater volume, since the primary challenge was just in hitting the target (generally much more vulnerable, but farther away, moving more quickly and with more maneuverability than your typical tank, needless to say), not in triggering the explosion to create a particular spacial and kinetic profile and the right distance, in order to penetrate primary armour. <b style="color:#19a0fd;">S</b><b style="color:#66c0fd">n</b><b style="color:#99d5fe;">o</b><b style="color:#b2dffe;">w</b><b style="color:#B27EB2;">Rise</b><b style="color:#d4143a"> let's rap</b> 22:38, 17 August 2023 (UTC)


 * The way my source (which I'm trying to fact-check) describes the whole matter is, it describes a form of spaced armor where a projectile first strikes and pierces a thin piece of sheet metal, which causes said projectile to tumble and strike the main armor plate (tough and somewhat deformable, i.e. not face-hardened) at an angle, thereby causing said projectile to break and allowing the armor to absorb the energy of the fragments through plastic deformation -- and then it goes on to allege that such an armor was installed on (at least some versions of) the Il-10 and that it could stop a 20-mm armor-piercing round. So, the intention was (allegedly) to increase resistance to ordinary armor-piercing rounds, not shaped charges (which wouldn't be of much use against aircraft, given that they require a direct hit, which is hard to score against an aircraft even with guided missiles, let alone a flak cannon) -- but, from what I know about the Russians (this is a Russian-language source I'm trying to check), it doesn't look all that plausible (the physical principle seems sound, but I don't think the Russians actually used this system on the Il-10 -- the Russian design philosophy is all about ease of manufacture, so this seems too sophisticated for them, and they also have always been much given to empty bragging, so I wouldn't put it past them to have made up the entire thing out of whole cloth!) 2601:646:9882:46E0:C990:4871:79E0:D481 (talk) 08:42, 18 August 2023 (UTC)


 * You close your last post in very much a similar way to how I was preparing to respond having read the first part: that is, more specifically, I was going to say this all sounds more or less feasible to me, but I can find no indication in the sources I turned up which specifically validate that this happened with Soviet service aircraft on the Eastern front. The purported benefit you describe, while I cannot validate that it passes engineering muster, it does at least provide an alternative rationale for using spaced armor on a low-altitude operations aircraft.  As you probably know, part of the reason for spaced armor was not just the dispersal of impact force ricocheting between the plates, but also the fact that tank-busting shells were designed to explode at a very specific range, creating a ballistic profile from the resulting fragments such as to maximize potential to penetrate the outer armor.  The spaced armor therefore served to frustrate that function from anti-tank munitions.  As you say, this is not a fit for purpose when trying to take down an aircraft.  By the end of the war, American vessels in the Pacific theatre especially were using flak shells that did have similar mechanisms for detecting nearby targets (some of the larger versions, utilized primarily to try to take down bombers in particular, employed radar, but there were other proximity fuze mechanisms as well).  But regardless of the specific mechanism when these fuzes were triggered, there would be no guarantee (and indeed, little chance) that the shell was directly on course to connect with the aircraft, so directing the force of the explosion in one particular direction was not ideal.  There was also less armor to penetrate in any event. The ballistic profile was therefore more generalized (the stereotypical globular explosion of ship-based high explosive or shrapnel-based flak weapons--supported of course by batteries of AA guns using more traditional ballistic munitions (which were also being increasingly effectively coordinated by radar and interconnected/semi-automated firing patterns by the war's end). The Germans basically had none of these advantages though (they had experimented with proximity fuzes for almost as long as the British and Americans, if I recall correctly, but did not have it implemented in any widely used ordinance at any point in the war.  Anyway, the context with regard to your source's claims is much different: the Il-2 and -10 were low altitude attack craft often supporting infantry and armour divisions.  Therefore they really would be especially concerned about the kinds of rounds contemplated in your source.  Whether or not the mechanics of the spaced armour really translate to the proposed advantage is rather a difficult thing to speculate upon, but the fact of the matter is that I see no other sources so far that validate that it was attempted.  That said, the sources I did see were very clear that the manufacturing techniques for equipping and maintaining the armour of these planes was very much set up to be distributed and amenable to some degree of variation: the sources I saw seem to be suggesting that this was more about the logistics of machining the relevant sheets in fairly variable plant conditions, but the circumstances could have lent themselves also to some degree of experimentation.  So, if I was Snopes, I'd give this one an "undetermined"?  It all adds up to possible (I mean, if nothing else, it could have been attempted and ended up being a terrible idea, or a mediocre idea that wasn't really thoroughly tested but which some engineers and field specialists bought into and continued to discuss for the remainder of and after the war). But as for direct confirmation in another source that it happened, I'm afraid I didn't find anything myself. <b style="color:#19a0fd;">S</b><b style="color:#66c0fd">n</b><b style="color:#99d5fe;">o</b><b style="color:#b2dffe;">w</b><b style="color:#B27EB2;">Rise</b><b style="color:#d4143a"> let's rap</b> 09:28, 18 August 2023 (UTC)
 * Right, I'm thinking that if anything, this might have been (a) a one-off experiment with a modified Il-10 which was never tried again because the benefit was judged to be not worth the complication, or (b) a technology which the Russians did actually use in combat, but for tanks, not aircraft (spaced armor would make more sense for tanks in any case), and which the official propaganda then bragged about later as a standard feature of the Il-10, in order to showcase the supposedly unique advancements of Russian aircraft design. 2601:646:9882:46E0:C990:4871:79E0:D481 (talk) 11:07, 18 August 2023 (UTC)